应激颗粒（SGs）是细胞质中的聚集物，在受到各种有害物质的刺激下，mRNA和特定蛋白质被困住。它们参与细胞的防御机制。目前，关于在离子辐射下形成SGs的机制以及其在肿瘤细胞放射敏感性中的作用尚不清楚。本研究调查了在不同剂量的光子照射下，头颈鳞状细胞癌（HNSCC）细胞系（具有不同放射敏感性）和作为参照的HeLa宫颈癌细胞系中SG形成的动力学。同时，还研究了SG的典型诱导剂亚砷酸钠（SA）的反应。通过SG特异蛋白的免疫标记和mRNA荧光原位杂交，检测和计量SG。此外，还利用核糖鲎酰化分析评估了细胞的翻译状态。为了确定活性氧生成（ROS）是否参与SG的形成，药物预处理诱导了ROS的清除或产生，研究了SCC61和SQ20B细胞系中的情况。不同剂量的光子照射导致了细胞质焦点的形成，这些焦点对不同SG标记物呈阳性。在HeLa、SCC61和Cal60放射敏感细胞中，SG的存在在暴露后30分钟至2小时逐渐增加。反之，SQ20B和FaDu放射抵抗细胞未形成SG。这些结果表明，光子照射敏感性和SG形成之间存在相关性。此外，在SCC61细胞中，通过二甲基亚砜清除ROS显著减少了SG的形成，这支持了它们在SG形成中的作用。然而，通过使用丁硫胺亚胺消耗谷胱甘肽的SQ20B细胞的倒置实验并未恢复这些细胞的SG形成。SGs形成是对放射线敏感但不敏感的HNSCC细胞对辐射的反应。有趣的是，与SA诱导的SGs相比，光子诱导的SGs在形态学和细胞定位上不同。此外，光子诱导的SGs与翻译抑制无关，而是依赖于氧化应激。 版权所有 © 2023年。由Elsevier Inc.出版。

Stress granules (SGs) are cytoplasmic aggregates in which mRNAs and specific proteins are trapped in response to a variety of damaging agents. They participate in the cellular defense mechanisms. Currently, their mechanism of formation in response to ionizing radiation and their role in tumor-cell radiosensitivity remain elusive.The kinetics of SG formation was investigated after the delivery of photon irradiation at different doses to head and neck squamous cell carcinoma (HNSCC) cell lines with different radiosensitivities and HeLa cervical cancer cell line (used as reference). In parallel, the response to a canonical inducer of SGs, sodium arsenite (SA), was also studied. Immunolabeling of SG-specific proteins and mRNA fluorescence in situ hybridization enabled SG detection and quantification. Furthermore, a ribopuromycylation assay was used to assess the cell translational status. To determine whether reactive oxygen species (ROS) were involved in SG formation, their scavenging or production was induced by pharmacological pretreatment in both SCC61 and SQ20B cells.Photon irradiation at different doses led to the formation of cytoplasmic foci that were positive for different SG markers. The presence of SGs gradually increased from 30 min to 2h post-exposure in HeLa, SCC61 and Cal60 radiosensitive cells. In turn, the SQ20B and FaDu radioresistant cells did not form SGs. These results indicated a correlation between sensitivity to photon irradiation and SG formation. Moreover, SG formation was significantly reduced by ROS scavenging using dimethyl sulfoxide in SCC61 cells, which supported their role in SG formation. However, a reciprocal experiment in SQ20B cells that depleted glutathione using buthionine sulfoximide did not restore SG formation in these cells.SGs are formed in response to irradiation in radiosensitive, but not in radioresistant, HNSCC cells. Interestingly, compared with SA-induced SGs, photon-induced SGs exhibited a different morphology and cellular localization. Moreover, photon-induced SGs were not associated with the inhibition of translation; rather, they depend on oxidative stress.Copyright © 2023. Published by Elsevier Inc.